Definition and classification of fabric Finishing
In general, the term “Finishing” applies to all of the operations both chemical and physical carried out to the fabric after production from weaving /knitting machine. From this point of view, Finishing can be considered as a very wide range of operations generally carried out in three stages, namely:
- Pretreatment that is scouring bleaching etc
- Coloration that is dyeing, printing etc
- Finishng that is the final stage of treatment of fabrics to prepare them for the consumer.
- A more restricted view of finishing is that of the third and final stage of the treatment and a simple definition of finishing is given as “finishing is the sequence of operations, other than scouring, bleaching, and coloring, to which fabrics are subjected after leaving the loom or knitting machine. Fabric direct from the loom is unattractive. To make the fabric attractive and acceptable to the consumer several finishing processes are applied. Sometimes special finishes are also applied to the fabric to make it serviceable for particular end use.
Finishing processes can be divided into two broad classes:
- Physical and
Physical and Mechanical Processes in Fabric Finishing
Physical and mechanical finishing processes are Brushing, Shearing, Pressing, Rainsing, Beetling, Calendaring, Folding, Various cutting operations etc.
The chemical finishing process is the application or deposition of chemical compounds into the fibers to improve the attractiveness and or serviceability. Sometimes fibers react with the chemical compounds l and form covalent bonds and the finishing effect can withstand several laundering operations. This type of finishing is often known as durable or permanent finishing.
Generally chemical finishing of cotton fabric improves the appearance (e.g. Mercerizing) and or improves serviceability (e.g. Easy care or durable press flame retardant, Water repellent etc.) Also chemical finishing may protect the cotton fabric against environmental condition such as protection from microbiological degradation. Also to avoid air pollution sophisticated exhaust mechanism for the processing are required.
Another most useful chemical finish cotton fabric is water repellence. Particularly rain coats, tent clothes, umbrella cloths, tarpaulins are needed with water repellent finishes. To produce a water repellent finish, hydrophobic substances are deposited on to the fiber either physically or chemically. Several methods are used, among which the flurochecmical finish is repellent to both water and oil. The fabric finish with flurochemical is also termed as stain resistant because liquid stains such as oil are also minimized. However, the flurochemical are very expensive consequently they can be used at lower concentration with convention water repellents to produce very effective results.
Untreated cotton fabric may be susceptible to microbiological degradation. Some cellulolytic enzymes are produced to break down the cellulose chains and as a result the life of the fabric is decreased. Bed sheet and other cloths used mainly in hospitals should be finished with anti-bacterial chemicals.
Considering research work has been carried out in the field and several chemicals and procedures have been developed, many of the proposed antibacterial finishes have not been commercialized due to their harmful effects on the environments. Extensive research work in these fields is still needed to establish more suitable processes.